DevOps Classroom notes 03/Jan/2026

k8s deployments

• Refer Here for official docs
• Deployments create replicasets which in turn creates pods
• Deployments have strategy
  • RollingUpdate: Roll new pods and kill older ones according to percentages or numbers defined (default is 25%)
  • Recreate: Delete all existing and recreate new pods

Example 1

• Lets write a deployment spec based on nginx containers

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: example-1
  labels:
    app: web
spec:
  minReadySeconds: 2
  replicas: 4
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: web
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
  template:
    metadata:
      labels:
        app: web
        env: dev
    spec:
      containers:
        - name: web
          image: nginx
          ports:
            - containerPort: 80

• with the workloads that support rollout (deployment, daemonset, statefulset) we can use kubectl rollout command
• our version 2 will be httpd containers

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: example-1
  labels:
    app: web
spec:
  minReadySeconds: 2
  replicas: 4
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: web
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
  template:
    metadata:
      labels:
        app: web
        env: dev
    spec:
      containers:
        - name: web
          image: httpd
          ports:
            - containerPort: 80

• Commands which we used
  • kubectl rollout status deployment example-1
  • kubectl rollout history deployment example-1
  • kubectl rollout undo deployment example-1 –to-revision=1

Annotations

• Annotations are also key pairs. They are designed for external tools to fetch info and add some metadata for tools.
• K8s has well known annotations with specific purposes

You are an expert in k8s, Give me a table of well known annonations and their purpose.

Also add 3 more tables for cloud specific annoations (AWS, Azure, GKE)

• Watch classroom video and add change-cause.

Exercise

• Push your docker images with tags v1 into docker hub
  • python
  • java
  • .net
  • react
• Write a deployment manifest with 2 replicas
  • now rebuild the docker image and upload the new tag v2
  • Now update the deployment with rollingupdate with 50% maxSurge adn 50% unavailable.